I. Field of the Invention
The present invention relates generally to trackside railway car handling equipment for positioning railway cars along a track for loading or unloading operations. More particularly, the present invention relates to train indexer systems that include dogs that engage the bogey frames of railcars and, specifically, to indexer systems that include mechanical systems for sensing the presence of bogey frames in conjunction with the operation of the dogs.
II. Related Art
Freight-hauling railway cars need to be precisely positioned proximate freight or cargo handling equipment during loading and unloading operations. Freight in the form of bulk cargo such as grain is typically loaded or unloaded with reference to stationary freight handling equipment such as chutes and conveyor equipment situated at fixed locations above or in pits beneath a specific portion of the track. Railcars for transporting grain or other such finely divided dry bulk agricultural commodities may be covered and designed with a plurality of spaced bottom discharge hopper bins or chutes accessing the main cargo storage volume. The chutes are closed by capstan-operated rack and pinion bottom closure gate systems.
In the loading and discharge operations, a connected engine roughly positions one end of a string of cars to be loaded or unloaded beneath or above the appropriate equipment at the desired fixed location. Because locomotives are not well suited for precisely positioning individual cars or even strings of cars along a railroad track, positioning devices known as train movers or positioners are located at fixed stations along the track. The positioning devices are generally in the form of “indexers”, or “progressors”. Indexers generally employ a pair of spaced “dogs”, which operate together. The dogs are heavy car-engaging members mounted on movable dog carriages which are operated along built-in auxiliary carriage tracks or guideways. In the case of systems designed to operate by pushing against railway car truck bogey frames, the guideways are located one on the outside of each of the track rails in juxtaposed parallel relation thereto to engage and simultaneously push against the spaced sides of a bogey frame, axle or other portion of a railcar to urge the car and others attached to it in a desired direction for a limited distance. The system then retracts and finds the next bogey frame or axle, etc. to repeat the process. The system can be stopped at any point in a cycle when the desired position is reached for loading or unloading a car.
Progressors designed to operate against bogey frames also have built-in guideways on the outside of each of the spaced rails with dogs that operate along each of the guideways. The systems are also spaced along the track and, rather than operating simultaneously against both sides of a bogey frame to move a car or string of cars, the dogs of a progressor are operated alternately, sequentially to “hand off” the car or string of cars alternating between dogs on opposed sides of the track.
Using either type system an entire string of connected cars may be advanced and loaded or unloaded, one car at a time. As with the indexer system, the progressor can be stopped at any point in the operating cycle when the desired position is reached.
The positioning devices of the present invention are indexer systems that utilize dogs that operate against the wheel truck bogey frames of the cars. The proper operation of these devices depends on the ability of the system to detect the presence of bogey frames and operate corresponding dogs accordingly. Many techniques have been employed to detect the presence of or locate wheel truck bogey frames. These include optical or mechanical devices that sense the presence of train wheels, mechanical devices that are linked to operate the dogs directly upon detection of the presence of a wheel truck bogey frame, techniques that include using the deflection of raised dogs striking carriage bogey frames from behind to sense those frames. Using the “dog” method, the first of two spaced opposed dogs encountering the bogey frame is pushed down from behind and the second dog which is also in the pushing posture engages the bogey frame as the dog carriage continues to move.
While such systems work quite well, the presence of auxiliary devices such as tripper rods which are used in conjunction with operating bottom discharge gates may interfere with using raised dogs as sensors. Direct connected mechanical systems are shown, for example, in U.S. Pat. Nos. 6,389,984 and 5,709,153. These also require additional mechanical linking devices. Thus, there remains a need to provide a simple mechanical truck carriage bogey frame detecting system that includes a simplified operating system for a corresponding pusher dog.